Ethionine and 2-Fluoroacetamide will be fed to rats and the normal liver tissue, pre-malignant nodule and hepatomas analyzed for various lipid types to determine if qualitative or quantitative changes in lipid content unique to these three tissues occurs. Enzymes involved in the metabolism of several lipids will be isolated and characterized in these three types of liver tissue to determine if a change in enzyme function accounts for the results obtained. Determine if changes in the above lipids in blood serum might be indicative of a pre-malignant or malignant state.